As a person who is athletic this was a hard thing for me until I became older. When you play sports you are obviously playing to win and to be better than the others. Always trying to figure out how you can beat the opponent.
Now that I am older I find that it is more important for me to improve myself and be better whether it is in a sport or living my life. I look to myself to see how I can improve instead of trying to figure out how to beat the other person.
What this has done is let me be more relaxed when I am competing because I have no one to beat but myself.